Portable metal cutting pyrotechnic torch

ABSTRACT

A portable metal-cutting pyrotechnic torch comprising a solid thermite fuel for pyrotechnics, an igniter and a thermally non-conducting handle. Further provided is a tubular body which preferably burns away with the composition.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates to a portable metal-cutting pyrotechnic torch and more particularly this invention relates to a metal-cutting pyrotechnic torch that uses thermite fuel and even more particularly, this invention relates to a hand-operated portable metal-cutting thermite-fueled pyrotechnic torch suitable for first responders, demilitarizing ordnance, underwater metal-cutting and other uses requiring hand-held portability.

[0003] 2. Statement of the Prior Art

[0004] The earliest effective technique for cutting metal utilizes an oxyacetylene flame to heat an area on a metal surface after which a gas stream of acetylene and mostly oxygen is directed to the heated area thereby oxidizing the metal surface. The force of the gas stream removes the oxide products of the combustion. For some applications this method is relatively fast and efficient if the use of large amounts of oxygen and acetylene under high pressure in heavy metal bottles does not present an impediment. However, this method is not efficient for cutting copper and aluminum and their alloys. Further, it is not efficient for cutting where high temperatures are required nor where underwater metal-cutting is to be done. In addition, the heavy bottles and hoses present a hazard for military operations during wartime. Consequently, the portability of this system is very limited and cumbersome. Underwater use is extremely sophisticated and require specialized equipment and high pressure air sources. This equipment is not practical to be carried by first responders and require some skill in use. Use of this equipment require special eye protection.

[0005] Arc-oxygen is another technique for cutting metal whereby an electrically conducting workpiece and an electrode is connected to a power source. An area on the metal workpiece is heated with an electric arc after which a jet stream of essentially oxygen is directed to the heated area thereby oxidizing the work piece while removing the oxidation products by the force of the jet stream. The oxygen can be supplied by a tube which also acts as the electrode. This tube will either be consumed during this operation or require some means to obviate this condition. This technique require a high voltage electric source as well as the oxygen as in the oxyacetylene technique. Again, this technique has no portability or practicality for first responders and little practicality in the field of military operations. This technique also require special eye protection.

[0006] Similarly, use of thermite techniques utilizing a reaction produced by passing a high-velocity stream of oxygen past by steel rods and rods of aluminum, magnesium and titanium and alloys where all of the rods are located in a steel tube. Again, there is the problem of the steel tube being consumed. Further, there is the lack of portability due to the need for oxygen under high pressure. There is some question of whether the temperature reached in this technique is suitable for demilitarizing ordnance which require a fast breach of its casing or risk great peril of safety. Certainly, this technique is not practical for first responders.

[0007] U.S. Pat. No. 4,371,771 issued to Faccini et. al. attempts to overcome the problem of the aforementioned art by a cutting torch for cutting or removing material by utilizing a high-velocity gas stream to promote combustion of the material whereby a hollow elongated structure with an adequate supply of aluminum for producing unstable aluminum oxides. In this patent it anticipates the assurance of a rapid break of military ordnance by exposing the casing to high temperature along with developing an exothermic reaction on the surface. But again, this technique require a large volume of oxygen under high pressure. Further, this technique, as with the other techniques, does not obtain high immediate heat transfer to the casing or workpiece.

[0008] U.S. Pat. No. 3,713,636 issued to Helms, et. al. discloses a incendiary cutting torch for underwater use and attempts to over come the use of high air pressures necessary for oxyacetylene use under water. He uses an incendiary torch charged with reactants and having a cylindrical housing with a nozzle readily attachable to a work-holding device. The nozzle is designed for high velocity jet produced by reactants contained in the torch. By the need for this torch to be attached to the workpiece does not allow for it to make an elongated cut. Further, this torch is not designed to be hand-held. Even further, the reactants utilized does not have high heat transfer qualities.

[0009] U.S. patent issued to Halcomb et. al. discloses a thermite composition for producing high-pressure, high-velocity gases. In this patent, it discloses oxidizing reagents selected from the group consisting of CuO, Cu₂O, Cr₂O, WO₃, Fe₂O_(3,) Fe₃O₄, MnO₂, and PbO_(2,) Oxidizable metals taken from the group consisting AlSi, AlMg, Mg and al and a high-temperature stable additive to enhance gas production which additive is taken from the group consisting of TiC, B4C, VC, SiN and TiN. He discloses his preferred embodiment to be 79.5% CuO, 17.5% Al and 3% SiC. He further discloses that his composition may be used in torches but does not specify what type of torches can be utilized. He further discloses that his composition may be modified to adjust the speed of its combustion but does not disclose how this is achieved. At the time of his disclosure, only metal cutting torches made of heavy metal construction had been disclosed for his type of composition. While his composition does not provide a composition for high heat transfer to a workpiece, it is usable where high pressure, high volume gaseous products are beneficial. However, he does not disclose the use of its composition in a torch that is portable and designed for hand-held use.

[0010] All of these cutting torches are not suitable for first responders such as firemen and policemen who often find themselves in an emergency life-saving situation requiring the need of a portable metal cutting torch. Further, none of these torches are suitable for demilitarizing ordnance because of their impracticality for field use, inability to achieve high temperatures for a quick breach of a casing and their impracticality in being supplied to small units. Even further, these torches are cumbersome, require skill to use and none of them can be conveniently carried by an individual. Those torches cannot be used for small projects such as arts and crafts.

[0011] It is therefore desirable for a metal cutting torch to be portable and hand held, able to cut quickly through thick metal, does not produce a light harmful to the eyes, reach high temperatures for demilitarizing ordnance, suitable for first responders, usable under water, environmentally safe, have a long shelf life and practical for military field use.

SUMMARY OF THE INVENTION

[0012] Applicant has overcome the perils and disadvantages of the prior art by providing a hand-held torch practical for first responders, usable underwater and having a temperature high enough for demilitarizing ordnance. Accordingly, applicants invention comprises a solid thermite fuel for pyrotechnics, an igniter and a thermally non conducting handle. Further provided is a tubular body which preferably burns away with the composition.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The intentions more readily understood by reference to the following drawings in which:

[0014]FIG. 1 is a drawing of a hand held cutting torch having a cylindrical body.

[0015]FIG. 2 is a cross sectional drawing of a hand held cutting torch having a solid thermite charge with a polymeric binder.

[0016]FIG. 3 is a cross sectional drawing of a hand held cutting torch having a solid thermite charge with a cylindrical body to contain the charge.

DETAILED DESCRIPTION OF THE INVENTION

[0017] Applicants invention is a portable metal-cutting pyrotechnic torch which is charged with a solid thermite fuel for pyrotechnics, an igniter and having a thermally non-conducting handle. The body of the torch may consist of a solid thermite fuel or a tubular body in which the solid thermite charge is disposed. When the torch has a body it preferably burns away with the composition.

[0018] A solid thermite fuel provided in applicants torch is disclosed in his co-pending application Ser. No. ______. In that application, applicant discloses a thermite composition for pyrotechnics having high heat transfer charactistics comprising a strongly reducible metal oxide, a thermally decomposable heat transfer agent consisting of Cu₂O, and a strong reducing agent. It is desirable that the stoichiometerics and mechanics of the thermite reaction is such that there is a substantial excess of oxygen. Also, other ingredients may be added to the composition such as gas generating compounds, binders, diluents and supplemental oxidizing agents.

[0019] The strongly reducible metal oxide is taken from the group consisting of FeO, Fe₂O₃, CoO, NiO, Cu₂O, CuO, Sb₂O₃, MoO₂, MoO₃, Cr₂ O₃, PbO₂, WO₂, and WO₃ or a combination thereof and is provided in the range of about 35-33% by weight. It is preferred that the strongly reducible metal oxide of the present invention is more reactive than the thermally decomposable heat transfer agent. Accordingly, the strongly reducible metal oxide is preferably taken from the group consisting of Fe₂O₃, NiO, CuO, and CoO. It is even more preferred that the strongly reducible metal oxide is CuO. The thermally decomposable heat transfer agent is Cu₂O and is provided in an amount of about 20-55% by weight. The strong reducing agent is taken from the group consisting of Al, Si, Zr, Be, Mg, Ba, Ti, and B and is provided in an amount of about 5-20% by weight. It is preferred that the strong reducing agent is taken from the group consisting of Al, Mg, Si and Be.

[0020] Other ingredients that may be added are gas generating compounds taken from the group consisting of metal carbides and metal nitrides and nitrates provided in the range of about 0-5% by weight. Diluents may be added taken from the group consisting of LiF, NiF₃, FeCl₃, AlF₃, NiF₂, CaF₂, CrF₂, CrCl₃, CaO, Na₂SO₄, SiO₂, KCl, TiO₂, CrF₃, MgCl₂, CaCl₂, NiF₃, FeCl₃, MgF₂, MnO, Fe₂O₃, B₂O₃, Mg₀, and Al₂O₃ or a combination thereof. The diluent is added in an amount to decrease the rate of the reaction for a particular desired purpose. Typically, the diluent will be provided in small amounts in the range of 0-2% by weight. It is preferred that the diluent is provided in the range of about 0-1.5% by weight. These diluents are chosen to further enhance the reaction of the invention. It should be understood that gas generating agents and supplemental oxidizing agents can also act as diluents.

[0021] Supplemental strong oxidizing agents are well known and are taken from the group consisting of metal oxides, chlorates, perchlorates, peroxides, nitrites and nitrates or a combination thereof. These supplemental oxidizing agents may be added from 0-20% by weight. The preferred supplemental strong oxidizing agent is NaClO₃. The supplemental oxidizing agent can also act as a diluent.

[0022] The binder is a thermally fugitive agent which is decomposable or vaporizable during drying or during the reaction. The binder is provided in the range of about 0-6% by weight. These binders are well known in the art. A preferred binder would is polyethylene glycol.

[0023] It is preferred that all of the components is provided in an average grain size under 10 microns. It is further preferred that the strong reducing agent is provided in an average grain size smaller than the other components. In a preferred embodiment of the invention, the composition is made by mixing the ingredients by means well known in the art. The mixture is then dried and degassed to minimize moisture and gas therefrom and then formed into a means in which the mixture will be ignited, for example, by electric arc, heated wire, laser, electromagnetic radiation, chemical reaction, blasting cap, detonator and the like. Upon ignition, the strongly reducible metal oxide reacts primarily to produce the exothermic thermite reaction. While some of the heat transfer component, Cu₂O, reacts in the thermite reaction, it is primarily heated and decomposes at 1800° C. by the reaction products of the redox reaction. Thereby copper metal substantially in the gaseous state and oxygen is released in the form of a flame propagating from the burning mixture. When CuO is the strongly reducible metal oxide, copper in the gaseous state further results from the CuO thermite reaction. This gaseous copper is also propagated with the flame. The resultant gaseous copper and oxygen is available to heat an objective and supply oxygen for oxidation. When the products of the reaction is impinged upon an object, intense heat is transferred instantly from the gaseous copper in terms of latent heat of fusion, latent heat of crystallization and thermal conductivity. The oxygen from the reaction is available for the object to be oxidized.

[0024] Reference is made to the drawing, FIG. 1. Handle 5 can be made of any thermally insulating material. It is also preferably non-combustible. It is preferable that the handle 5 is removably attached to body 1 so that it can fit on either end of the Body 1 either as a cover over striker 3 or a handle fitted on the opposite end. As shown in FIG. 2 and FIG. 3, Handle 1 has disposed within a Plug 4 which is secured in Handle 1 by an adhesive. The distance A from the end of Handle 5 to Plug 4 is sufficient that the handle can be hand held and away from the burning Body 1. The Handle 5 may be of various designs and attached to Body 2 by means well known in the art.

[0025] Reference is now made to FIG. 2 wherein a preferred embodiment of applicant's torch, applicant chooses to use a thermite charge using the composition comprising the CuO as the strongly reducible metal oxide provided in the amount of 44% by weight, Al as the strong reducing agent provided in the amount of 10% by weight, Cu₂O is the thermally decomposable heat transfer agent provided in the amount of 29% by weight, NaClO₃ as the supplemental strong oxidizing agent provided in the amount of 11% by weight and a binder consisting of polyurethane polymer provided in the amount of 5% by weight and an epoxy curing agent in the amount of 1%. All of the ingredients are provided in an average size of less than 10 microns.

[0026] This thermite charge making up Body 1 is chosen because when ignited, it releases a stream of gaseous products, which includes the heat transfer agent and oxygen, at a force sufficient to instantaneously heat a metal surface, cause combustion of the metal surface and remove combustion products of that metal surface. Thereby, this torch is capable of cutting metal in the same manner as an acetylene torch, but with greater ease because of the superior heat transfer characteristics of the thermite composition.

[0027] The polymeric binder is mixed with a curing agent to form a slurry as is well known in the art. The CuO, Cu₂O, Al and NaClO₃ is added and mixed into a homogeneous mixture. Care must be taken that the mixture is a homogeneous mixture thereby avoiding cracks which result in discontinuities between fuel and oxidizer with the matrix resulting in an irregular burn and burn rate. The mixture is poured into a cylindrical mold 0.750 inch in diameter and 12 inches long. The diameter of the torch body is determined by the thickness of metal needed to be cut. A 0.750 diameter torch can cut metal 0.50 inch thick with ease. A larger diameter torch can cut metal thicker. The mixture is heated to an elevated temperature to effect polymerization. The ingredients in this embodiment is limited to those which do not react at ambient or at the elevated temperatures for polymerization. This molded composition comprise Body 1 in FIG. 2.

[0028] The igniter may be an electric arc, heated wire, laser, electromagnetic radiation, chemical reaction, blasting cap, detonator and the like. In this embodiment of the invention, the Igniter 2 is that which is the solid chemical type capable of reaching a temperature of at least 1000° F. as commonly used for fusees. An inflammable igniter compound of the solid hard variety commonly known as a “hard head” is affixed to an end of the cylindrical molded thermite composition by a combustible adhesive compound known in the art. The strike button 3, which is a chemical solid ignitable by abrasion, is inserted on the end of the Igniter 2 by methods well known in the art of making fusees.

[0029] On the other end of the molded thermite compound is fitted a thermally non-conducting and preferably non-combustible handle 4 such as one made of sheet of paper rolled into a cylindrical shape of a size to force fit on body 1. By thermally non-conducting, it is meant that it can be held by hand preferably with protection while the thermite composition is burning. The handle is long enough so that the hand is far removed from the end of the thermite mold indicated by distance A. While the aforementioned embodiment is a preferred embodiment, it is not the most preferred embodiment as the solid body of the thermite mold and the “hard head” may be subject to impact causing breakage which could reduce the utility of the torch.

[0030] Reference is now made to FIG. 3. In that most preferred embodiment of the invention, applicant chooses to use a thermite charge 1 of the composition comprising the CuO as the strongly reducible metal oxide provided in the amount of 46% by weight, Al as the strong reducing agent provided in the amount of 10% by weight, Cu₂O is the thermally decomposable heat transfer agent provided in the amount of 31% by weight, NaClO₃ as the supplemental strong oxidizing agent provided in the amount of 15% by weight and a binder consisting of polyethylene glycol provided in the amount of 1% by weight, All of the ingredients are provided in an average size of less than 10 microns.

[0031] A body 6 in FIG. 3, made to contain the thermite charge 1, may be made of any material suitable for containing the thermite charge, such as metal, plastic, fabric, paper and the like. It is preferred, however, that the body is made of a material such a paper that burns away as the thermite charge is burned. Accordingly, a preferred Body 6 is prepared for the thermite charge by rolling a sheet of paper into a tubular form with walls formed of several layers of the sheet. The tube is 0.75 inch in diameter and 14.0 inches long. Again, the diameter is determined by intended use. A thin end formed of a single layer is folded down to close the end and fastened by cement or glue as well known in the art of making cylindrical bodies for fusees. The paper is a type that is easily burned away with the composition. The paper may actually burn a short distance behind the burning of the molded thermite charge.

[0032] The thermite charge is mixed with the binder by conventional means until the mixture is homogeneous. Homogeneity, again is important so that all of the ingredients are in intimate contact in a uniform mixture with all of the other ingredients. The charge is dried and degassed by conventional means care being taken not to heat the mixture to near the ignition temperature. After drying and degassing, the mixture is pressed into the paper Body 6 to a depth of 12.0 inches with a predetermined density based upon experimental burning rates. It is desired that the thermite charge burn at a rate of about 30 seconds per two inches, resulting in a four minute burn for a 8.0 inch torch. After the tube is packed with the thermite charge, an Igniter 2 is then inserted in the end of the paper body and caused to be adhered to the thermite charge by a combustible adhesive, glue or cement. A strike button 3 is inserted on the end of the igniter.

[0033] On the closed end of the body is fitted a thermally non-conducting Handle 5 which is made of a sheet of paper rolled into tubular shape and having disposed therein a Plug 4 which is secured within Handle 5 by an adhesive. By thermally non-conducting, as above, it is meant that it can be held by hand, preferably with protection while the thermite composition is burning. The handle is long enough, distance A, so that the hand is far removed from the end of the thermite mold.

[0034] While applicant invention is described with regard to using the thermite composition of his co-pending application, other compositions not described in that application can be used. It is only necessary that the reaction rates suitable for this torch are used and suitable high temperatures are reached. It is desirable that the composition used in this invention reach a temperature of at least 2000° C. While the compositions may not have the heat transfer characteristics of applicants co-pending application. They can be used in applicants invention. Suitable gas generating agents are necessary to propagate a flame. It is preferable that the composition is environmentally safe, stable at ambient conditions, and have a long storage life.

[0035] Compositions such as that which is described in U.S. Pat. No. 4,963,203 issued to Halcomb et. al. can be used in applicant's invention so long as it is adjusted to have a relatively slow burn rate and the high volume and high pressure of emitted gas is reduced to propagate a flame of about 6.0 to 10.0 inches.

[0036] It can be seen that applicant described his invention with regard to specific embodiments, any one skilled in the art may be able modify the torch without departing from applicant's inventive intent. Therefore any such modifications are intended to be covered by this specification and claims. 

What is claimed is:
 1. A portable metal-cutting pyrotechnic torch comprising: (a) a solid thermite fuel for pyrotechnics; (b) an igniter; and (c) a thermally non-conducting handle connected to the solid thermite fuel.
 2. The torch of claim 1, wherein: (a) the solid thermite fuel is contained in a tubular body; (b) the handle is connected to the tubular body; and (c) the igniter comprises a solid inflammable material and a strike head.
 3. The torch of claim 1, wherein: (a) the solid thermite fuel is contained in a tubular body; (b) the thermite fuel comprises a strongly reducible metal oxide, Cu₂O, and a strong reducing agent; and (c) the handle is connected to the tubular body.
 4. The torch of claim 1, wherein: (a) the solid thermite fuel is contained in a tubular body; (b) the thermite fuel comprises CuO, Cu₂O, and Al; and (c) the handle is connected to the tubular body.
 5. The torch of claim 1, wherein: (a) the solid thermite fuel is contained in a tubular body; (b) the thermite fuel comprises CuO provided in an amount in the range of about 35-55% by weight, Cu₂O provided in an amount in the range of about 20-55% by weight, and Al provided in the range of about 5-20% by weight; and (c) the handle is connected to the tubular body.
 6. The torch of claim 1, wherein: (a) the solid thermite fuel is contained in a tubular body; (b) the thermite fuel comprises CuO, Cu₂O, NaClO₃ and Al; and (c) the handle is connected to the tubular body.
 7. The torch of claim 1, wherein: (a) the solid thermite fuel is contained in a tubular body; (b) the thermite fuel comprises CuO, Cu₂O, NaClO₃ Al, and a binder; and (c) the handle is connected to the tubular body.
 8. The torch of claim 1, wherein: (a) the solid thermite fuel is contained in a tubular body; (b) the thermite fuel comprises CuO provided in an amount in the range of about 35-55% by weight, Cu₂O provided in the range of about 20-55% by weight, NaClO₃ provided in the range of about 0-20% by weight, Al provided in the range of about 5-20% by weight, and a binder provided in the range of about 0-2% by weight; and (c) the handle is connected to the tubular body.
 9. The torch of claim 1, wherein: (a) the solid thermite fuel is contained in a tubular body; (b) the thermite fuel comprises a strongly reducible metal oxide, Cu₂O, a strong reducing agent, and a supplemental strong oxidizing agent; and (c) the handle is connected to the tubular body.
 10. The torch of claim 1, wherein: (a) the solid thermite fuel is contained in a tubular body; (b) the thermite fuel comprises a strongly reducible metal oxide, Cu₂O, a strong reducing agent, a supplemental strong oxidizing agent and a binder; and(c) the handle is connected to the tubular body.
 11. The torch of claim 1, wherein: (a) the solid thermite fuel is contained in a tubular body; (b) the thermite fuel comprises CuO provided in an amount of about 46% by weight, Cu₂O provided in the range of about 31% by weight, NaClO₃ provided in the amount of about 12% by weight, Al provided in the amount of about 11% by weight, and a binder provided in the amount of about 1% by weight; and (c) the handle is connected to the tubular body. 